This invention relates to seals for preventing bodily fluids, irrigation fluids, or distention fluids from escaping from a medical instrument inserted within a patient's body. In particular, the invention relates to elastomeric seals for accessory instrument ports in endoscopic medical instruments.
Endoscopic instruments include accessory ports for introducing other instruments into the body of a patient. For example, a catheter or guide wire may be introduced through such a port into the vascular system of a patient. Endoscopes include a means for providing a seal (1) when no accessory is in the port, (2) as an accessory is introduced into the port, (3) as the accessory is manipulated for its intended purpose, and (4) as the accessory is withdrawn from the port. Without such sealing capabilities, blood and other bodily fluids, as well as introduced fluids, can escape from the port, leaking or spraying medical personnel and equipment with the fluids. These fluids may contain viruses and other biological agents that pose a risk to the personnel or that contaminate equipment.
To address the problem, endoscopes conventionally have included a valve in a location distal to the accessory port. If no accessory is in place, the valve is closed to prevent bodily fluids from escaping from the instrument. If the valve is opened so that an accessory may be inserted through the port, the port includes an elastomeric seal capable of providing an aperture through which the accessory may be passed. To provide an aperture, a slit may be formed through the center of the seal, which expands to receive the accessory, forming a seal between the accessory and the endoscope port.
Prior art devices of this nature are seen in U.S. Pat. No. 4,809,679 to Shimonaka et al. and U.S. Pat. No. 5,613,956 to Patterson et al. The '679 patent describes an elastic plug body with a slit for use in an endoscope. The plug fits into an endoscope frame above a valve also positioned in the frame. The plug or the frame includes projections oriented perpendicular to the slit to urge the slit closed when the plug is fitted in the frame. The '956 patent relates to an expandable aperture aligned with a subjacent, slitted layer of material.
One of the drawbacks of such devices is that between the time an accessory is removed from the endoscope and the accessory-port valve is closed, blood or other bodily fluid can leak or spray from the port because the seal does not effectively self-close. This happens because the seal around the accessory may be distorted by an accessory passing through and stretching the aperture. In the case of the '956 patent, this has to do with the aperture being directly adjacent to the slitted layer. While it may help to make a seal with a tighter fitting aperture or gasket, a tighter fit compromises the slideability of the accessory through the port.
For the foregoing reasons, there is a need for an improved seal that not only provides an effective seal around a situated accessory, but also provides a leak-free seal as an accessory is withdrawn or inserted through an accessory port. With such a seal, it would be possible to eliminate the valve from the accessory port. By eliminating the valve, endoscopes could be made that are simpler and less expensive to construct. By eliminating the valve, surgeons could operate endoscopes more easily--ease of use is always an important factor in surgery, particularly in minimally-invasive, endoscopic procedures where precision and delicateness are needed.
Unfortunately, until the present invention, there has not been a seal of simple construction that addresses the foregoing problems and needs.